The present invention relates to a control apparatus for a copying machine which employs counts of timing pulses appearing in synchronism with the rotation of a photosensitive drum to control the sequence of a copy process including charging, exposing, developing, transferring, fixing and sheet discharging steps.
Generally, a copying machine is furnished with various sizes or formats of transfer or copy sheets and causes a specific format of sheets conforming with the size of a document to be selected and processed by the machine.
With this in view, a copying machine usually performs sequence control of a copy process for the largest sheet format the machine can handle, regardless of the sheet format which was selected. For instance, where the largest usable format of sheets is A3, an optical scanning assembly of the machine will be moved a distance necessary for processing A3 sheets so as to scan a document even though the format of sheets actually used may be B5.
Such a sequence control, however, offers an obstruction to an increase in the operating speed of the machine or a decrease in the copying time.
A possible solution to this problem may be employing various kinds of sequence control programs for individual usable formats of sheets and selecting them in accordance with the format of sheets used. This is not acceptable, however, because a disproportionately large number of parts are needed which results in an increase in the cost.